Cancer-associated point mutations in isocitrate dehydrogenase 1 and 2 (IDH1, IDH2) confer a neomorphic enzymatic activity: the reduction of alpha-ketoglutarate (?KG) to D-2-hydroxyglutaric acid (2HG), which is proposed to act as an oncogenic metabolite by inducing hypermethylation of histones and DNA. While selective inhibitors of mutant IDH1 and IDH2 have been identified and are currently under investigation as potential cancer therapeutics, the mechanistic basis for their selectivity is not yet well-understood. A high-throughput screen for selective inhibitors of IDH1 bearing the oncogenic mutation R132H identified Compound 1, a bis-imidazole phenol that inhibits 2HG production in cells. We investigated the mode of inhibition of Compound 1 and a previously published IDH1 mutant inhibitor with a different chemical scaffold. Steady-state kinetics and biophysical studies show that both of these compounds selectively inhibit mutant IDH1 by binding to an allosteric site, and that inhibition is competitive with respect to Mg(2+). A crystal structure of Compound 1 complexed with R132H IDH1 indicates that the inhibitor binds at the dimer interface and makes a direct contact with a residue involved in binding of the catalytically essential divalent cation. These results show that targeting a divalent cation binding residue can enable selective inhibition of mutant IDH1, and suggest that differences in magnesium binding between wild-type and mutant enzymes may contribute to the inhibitors' selectivity for the mutant enzyme.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.